IN BRIEF

Science / Medicine : Colorado River Seen in Peril

The Colorado River is the most endangered river in America due to an upstream dam that is choking its flow through the majestic Grand Canyon, an environmental group said last week.

Two Alaskan rivers--the Alsek and Tatshenshini--and the American River of California also led the list of the nation's 10 "most endangered" rivers, as compiled by American Rivers, a nonprofit river protection group.

"Our hope is that this endangered rivers list helps protect the specific rivers, and that it raises river conservation to the top of the nation's environmental agenda," said Kevin Coyle, president of the group.

Other rivers on the list, in order, were Maine's Penobscot River, Pennsylvania's Susquehanna River, the Upper Mississippi River, the Columbia and Snake rivers in the Northwest, the Gunnison River in Colorado, the Passaic River in New Jersey and North Carolina's New River.

Coyle said the Colorado is the most endangered due to multiple threats posed by the Glen Canyon Dam, which is located 16 miles upstream from Grand Canyon National Park.

Environmentalists said the dam's operations cause huge fluctuations in water levels in the Grand Canyon, wreaking havoc on the Colorado's trout and other fish, including the federally protected humpback chub.

The rise and fall in water levels, along with the entrapment of silt by the dam, also is eroding the river's fragile beaches, which are essential to vegetation and a wide variety of bird and animal life.